The present invention relates to a honeycomb structure for carrying a catalyst to be used in an exhaust gas purification device of heat engines such as internal combustion engines or the like or a combustion device such as boilers or the like, or in a reforming device for liquid fuel or gaseous fuel, or a honeycomb structure used as a filter.
The honeycomb structure carrying a catalyst component has conventionally been used in an exhaust gas purification device of heat engines such as internal combustion engines or reforming devices for liquid fuel or gaseous fuel. In addition, it is known that a honeycomb structure is used as a filter for trapping a particulate matter contained in dusty fluid such as exhaust gas from a diesel engine.
Such a honeycomb structure is exposed to a rapid temperature change and local generation of heat due to exhaust gas, and non-uniform temperature distribution inside is easy to be caused, thereby causing a problem of having a crack. In order to solve such a problem, there has been proposed a method to relieve thermal stress to act on a structure by unitarily joining plural honeycomb segments with an elastic bonding material to form an integrated honeycomb structure.
However, when multiple honeycomb segments are joined to be used as one honeycomb structure, because the outer walls to be joining planes of a honeycomb segment was smooth conventionally, joining strength was weak and the joining of honeycomb segments became loose or disjointed due to vibration or exhaust back pressure in use, and sometimes a honeycomb segment shifted or fell to pieces.
The present invention has been made in view of such conventional circumstances and aims to provide a honeycomb structure excellent in durability by which honeycomb segments do not move due to vibration or exhaust back pressure in use.
According to the present invention, there is provided a honeycomb structure comprising multiple honeycomb segments joined by means of a bonding material, each of the honeycomb segments having a plurality of passages which are defined by partition walls and extend in an axial direction,
wherein flatness of outer walls to be joining planes of the honeycomb segments is 0.2 mm or more.
In the present invention, xe2x80x9couter walls to be joining planesxe2x80x9d means planes of each outer wall to be jointed with a bonding material except for a corner part including a rounded corner. In addition, xe2x80x9cflatnessxe2x80x9d is as defined by JISB0621-1984.